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# Copyright (c) 2016 Ruby-GNOME2 Project Team
# This program is licenced under the same licence as Ruby-GNOME2.
#
=begin
= Text View/Hypertext
Usually, tags modify the appearance of text in the view, e.g. making it
bold or colored or underlined. But tags are not restricted to appearance.
They can also affect the behavior of mouse and key presses, as this demo
shows.
=end
class HypertextDemo
def initialize(main_window)
initialize_window(main_window)
initialize_cursors(main_window)
initialize_view
@view.signal_connect "key-press-event" do |_widget, event|
case event.keyval
when Gdk::Keyval::KEY_Return, Gdk::Keyval::KEY_KP_Enter
iter = @buffer.get_iter_at_mark(@buffer.get_mark("insert"))
follow_if_link(iter) if iter
end
false
end
# Links can also be activated by clicking or tapping.
@view.signal_connect "event-after" do |widget, event|
if event.is_a?(Gdk::EventButton) && event.button == 1
buffer = widget.buffer
# we shouldn't follow a link if the user has selected something
range = buffer.selection_bounds
return false if range && range[0].offset != range[1].offset
x, y = widget.window_to_buffer_coords(:widget, event.x, event.y)
iter = widget.get_iter_at_location(x, y)
follow_if_link(iter) if iter
else
false
end
end
@view.signal_connect "motion-notify-event" do |widget, event|
x, y = widget.window_to_buffer_coords(:widget, event.x, event.y)
set_cursor_if_appropriate(widget, x, y)
widget.window.pointer
false
end
sw = Gtk::ScrolledWindow.new
sw.set_policy(:automatic, :automatic)
@window.add(sw)
sw.add(@view)
show_page(1)
sw.show_all
end
def run
if !@window.visible?
@window.show_all
else
@window.destroy
end
@window
end
private
def initialize_window(main_window)
@window = Gtk::Window.new(:toplevel)
@window.screen = main_window.screen
@window.title = "Hypertext"
@window.set_default_size(450, 450)
@window.border_width = 0
end
def initialize_cursors(main_window)
display = main_window.display
@hand_cursor = Gdk::Cursor.new("pointer", :display => display)
@regular_cursor = Gdk::Cursor.new("text", :display => display)
end
def initialize_view
@view = Gtk::TextView.new
@view.wrap_mode = :word
@view.left_margin = 20
@view.right_margin = 20
@buffer = @view.buffer
end
# Fills the buffer with text and interspersed links. In any real
# hypertext app, this method would parse a file to identify the links.
def show_page(page)
@buffer.text = ""
case page
when 1
generate_page_1
when 2
generate_page_2
when 3
generate_page_3
end
end
def generate_page_1
iter = @buffer.get_iter_at(:offset => 0)
@buffer.insert(iter, "Some text to show that simple")
insert_link(iter, "hyper text", 3)
@buffer.insert(iter, " can easily be realized with ")
insert_link(iter, "tags", 2)
@buffer.insert(iter, ".")
end
def generate_page_2
iter = @buffer.get_iter_at(:offset => 0)
@buffer.insert(iter, <<-EOF)
A tag is an attribute that can be applied to some range of text.
For example, a tag might be called "bold" and make the text inside
the tag bold. However, the tag concept is more general than that;
tags don't have to affect appearance. They can instead affect the
behavior of mouse and key presses, "lock" a range of text so the
user can't edit it, or countless other things.\n
EOF
insert_link(iter, "Goback", 1)
end
def generate_page_3
iter = @buffer.get_iter_at(:offset => 0)
tag = @buffer.create_tag(nil,
"weight" => Pango::FontDescription::WEIGHT_BOLD)
@buffer.insert(iter, "hypertext:\n", :tags => [tag])
@buffer.insert(iter, <<-EOF)
machine-readable text that is not sequential but is organized
so that related items of information are connected
EOF
insert_link(iter, "Go back", 1)
end
def insert_link(iter, text, page)
tag = @buffer.create_tag(nil,
"foreground" => "blue",
"underline" => Pango::AttrUnderline::SINGLE)
tag.page = page
@buffer.insert(iter, text, :tags => [tag])
end
# Looks at all tags covering the position of iter in the text view,
# and if one of them is a link, follow it by showing the page identified
# by the data attached to it.
def follow_if_link(iter)
tags = iter.tags
tags.each do |tag|
if tag.page
show_page(tag.page)
break
end
end
end
# Looks at all tags covering the position (x, y) in the text view,
# and if one of them is a link, change the cursor to the "hands" cursor
# typically used by web browsers.
def set_cursor_if_appropriate(text_view, x, y)
iter = text_view.get_iter_at_location(x, y)
return unless iter
hovering = false
tags = iter.tags
tags.each do |tag|
if tag.page
hovering = true
break
end
end
if hovering != @hovering
@hovering = hovering
window = text_view.get_window(:text)
window.cursor = @hovering ? @hand_cursor : @regular_cursor
end
end
end
module Gtk
class TextTag
attr_accessor :page
end
end
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